Sun Path Analysis Statement

Sun Path Analysis Statement March 2025

Following submission of the previous application, concerns were raised in relation to the loss of light to the primary habitable rooms of the five apartments at the rear of Isle Of Alanis Apartments and the following had to be considered :

potential loss of light/overshadowing; potential overbearing impact upon outlook; and potential overlooking resulting in a loss of privacy.

When considering the impact on neighbours’ sunlight, there is a test that considers the hours of sunlight a window will receive over a 12 month period. Because the test relates only to sunlight, only windows facing within 90 degrees of due south are considered under the methodology contained with the BRE document Site Layout Planning for Daylight & Sunlight. The guidance is that main windows should receive at least 25% of the ‘annual probable sunlight hours’ for a 12 month period. This should include 5% of the total probable sunlight hours over the winter months between 21 September and 21 March. It recommends that a space where sunlight is required should receive at least two hours of sun over at least half its area on 21 March.

For this particular site, it was requested that a more detailed study of sunlighting potential be carried out with shadow plotting which we have completed. This involves producing plans showing the location of shadows at different times of day and year. Where there are existing open spaces or in this case building elevations with windows to habitable rooms, ‘before’ and ‘after’ shadow plots showing the difference that the proposed building makes will be required. In interpreting the impact of such differences, it must be observed that nearly all structures will create areas of new shadow, and some degree of transient overshadowing of a space or elevation is to be expected.

The equinox (21 March) is confirmed as the best date for which to prepare shadow plots as it gives an average level of shadowing. Lengths of shadows at the autumn equinox (September 21) will be the same as those for March 21, so a separate set of plots for September is not required. Clock times of the September shadows will be one hour later, because British Summer Time (BST) will be in force. Shadow plots state clearly whether the time of the plot is in Greenwich Mean Time (GMT) or BST. BST is currently in force from April to October inclusive.

Plots for summertime (for example 21 June) have been completed as they show the reduced shadowing then, although it should be observed that June 21 represents the best case of minimum shadow, and that shadows for the rest of the year will be longer. Conversely if winter shadows (for example December 21) are plotted, even low buildings will cast long shadows. In a built up area like this site, it is common for large areas of the ground or elevation to be in shadow in December which can be seen in the models.

The BRE guidance applies both to new gardens and amenity areas and to existing ones which are affected by new developments. If an existing garden or outdoor space is already heavily obstructed then any further loss of sunlight should be kept to a minimum. If less than half the space receives two or more hours of direct sunlight on 21 March, and a new development reduces that area to less than 0.8 times its former size, then this loss of sunlight is significant. This obviously is not the case here with the proposed new development.

Whilst analysing the impact of the proposed building on the existing apartments it confirms that there is only a small loss of direct sunlight in the summer months, but is clearly within the BRE guidelines of acceptability.

For interiors, access to sunlight can be quantified. BS EN 17037[1] recommends that a space should receive a minimum of 1.5 hours of direct sunlight on a selected date between 1 February and 21 March with cloudless conditions. It is suggested that 21 March (equinox) be used. The medium level of recommendation is three hours and the high level of recommendation four hours. For dwellings, at least one habitable room, preferably a main living room, should meet at least the minimum criterion. From the studies undertaken the 5 apartments in the Isle Of Alanis annex surpass these requirements with all apartments obtaining over a minimum of 6 hours of Direct Sun Light and the higher apartments up to nearly 8 hours.

The windows on the adjacent buildings also pass the 45-degree light rule and also the 50-50 rule for the right to light.

The shadow path analysis produced shows the most significant effects on the ground level, and obviously the windows further up the building are less effected.

It’s important to remember that rights of light is not a right to direct sunlight. Rather, it entitles the beneficiary to an acceptable minimum level of natural illumination, not the sun’s direct rays.

Please see Direct Sun Path Diagrams confirming the loss of direct sun light to the existing apartments at the rear annex of Isle Of Alanis Apartments from the proposed building for the months specified in your email below.

Below is the amount of time that there is no direct sunlight to the room caused by the proposed new building into either window of the habitable living room :

For June MP-SPA-07 please note the following : 3rd Floor Apartment - No Loss Of Direct Sun Light to room 2nd Floor Apartment - Approximately 30 minutes Loss Of Direct Sun Light to room 1st Floor Apartment - Approximately 60 minutes Loss Of Direct Sun Light to room Ground Floor Apartment - Approximately 100 minutes Loss Of Direct Sun Light to room Lower Ground Floor Apartment - Approximately 110 minutes Loss Of Direct Sun Light to room For December MP-SPA-08 please note the following : 3rd Floor Apartment - Approximately 10 minutes Loss Of Direct Sun Light to room 2nd Floor Apartment - No Loss Of Direct Sun Light to room 1st Floor Apartment - No Loss Of Direct Sun Light to room Ground Floor Apartment - No Loss Of Direct Sun Light to room Lower Ground Floor Apartment - No Loss Of Direct Sun Light to room For March / September MP-SPA-09 please note the following : 3rd Floor Apartment - Approximately 45 minutes Loss Of Direct Sun Light to room 2nd Floor Apartment - Approximately 70 minutes Loss Of Direct Sun Light to room 1st Floor Apartment - Approximately 145 minutes Loss Of Direct Sun Light to room Ground Floor Apartment - Approximately 145 minutes Loss Of Direct Sun Light to room Lower Ground Floor Apartment - Approximately 145 minutes Loss Of Direct Sun Light to room

Although the proposed new development will block the sea views to these apartments, they still have the main unrestricted southerly views out over the harbour and across Ramsey up to the mountains.

With the clarification in the new submitted drawings and Sun Path Analysis information, the new proposed building does not create an unacceptable level of light or overshadowing, have overbearing impact upon outlook or overlooking resulting in a loss of privacy to the apartments in the rear annexs of the Isle Of Alanis Apartments.

No windows on the proposed building face on to the existing windows of the apartments in Isle Of Alanis. The rear balconies have been provided with solid end panels to block any overlooking views directly in to the existing habitable room windows and the height of the top floor solid panel has been extend to prevent any potential overlooking. The bathroom windows of the new proposed apartment building which are closest to the Isle Of Alanis annex apartment windows, are to be of obscure glazing.

Therefore the proposed new development would not significantly adverse the visual amenities of neighbouring properties sufficient to warrant a refusal. The amendments to the proposed development have further reduced these perceived issues.